X-ray imaging has been used in the medical field and for radiology in general, such as non-destructive testing and x-ray computed tomography. Conventional radiography systems use x-ray absorption to distinguish differences between different materials, such as normal and abnormal human tissues.
Current x-ray sources typically incorporate wound filaments or small emitters, such as, for example, tungsten, tungsten alloys, or lanthanum hexaboride structures. An emphasis has been on developing point emitters that generally provide very small sources of electrons, which, in turn, can provide an approximate point source of x-rays. However, current x-ray point sources, particularly wound filament structures, if used to provide larger and, in particular, spatially uniform area x-ray sources, typically do not provide a spatially uniform x-ray emission field, due to artifacts in the uniformity of the emitted field of x-rays, generally resulting from nonuniform electron area impact patterns.